In a three-dimensional NAND flash memory in which memory cells are three-dimensionally arranged, a high degree of integration and a low cost are achieved. In order to improve a read characteristic of the three-dimensional NAND flash memory, a positive feedback-type three-dimensional NAND flash memory is suggested in which a p-type semiconductor region is provided at one end of a memory string. In the positive feedback-type three-dimensional NAND flash memory, a memory cell transistor has a steep subthreshold slope, resulting in an improvement of a read characteristic. In order to achieve an even higher performance of the three-dimensional NAND flash memory, it would be desirable to achieve further improvements in the read characteristic of the positive feedback-type three-dimensional NAND flash memory.